我在谷歌上搜索了几个小时试图弄清楚这一点。
基本上我的情况是我必须找到一种方法来逆转由 .off() 方法引起的事件处理程序的删除。
换句话说，我希望能够使用另一个按钮重新打开 p 标记的事件处理程序。我怎样才能做到这一点？这是我的代码示例:
<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script>
$(document).ready(function(){
$("p").on("click", function(){
$(this).css("background-color", "pink");
});
$("#turn-off").click(function(){
$("p").off("click");
$('p').css("background-color", "white");
});
$("#reverse").click(function(){
//???
});
});
</script>
</head>
<body>
<p>Click this paragraph to change its background color.</p>
<p>Click the button below and then click on this paragraph (the click event is removed).</p>
<button id='turn-off'>Remove the click event handler</button>
<button id='reverse'>Reverse the removal of the click event handler</button>
</body>
</html>请您参考如下方法:
重新打开它只是再次调用.on。而且，由于您再次调用 .on，因此您需要提供所有参数 - 就像第一次一样。
为了更简单，您可以将调用 .on 的代码移至一个函数，并在 #reverse 点击逻辑中使用它。
<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script>
$(document).ready(function(){
function turnOn() {
$("p").on("click", function(){
$(this).css("background-color", "pink");
});
}
turnOn(); // initial setup
$("#turn-off").click(function(){
$("p").off("click");
$('p').css("background-color", "white");
});
$("#reverse").click(function(){ // or, simply: $("#reverse").click(turnOn);
turnOn();
});
});
</script>
</head>
<body>
<p>Click this paragraph to change its background color.</p>
<p>Click the button below and then click on this paragraph (the click event is removed).</p>
<button id='turn-off'>Remove the click event handler</button>
<button id='reverse'>Reverse the removal of the click event handler</button>
</body>
</html>另外，我建议您使用namespaced events ，将来应该会为您省去一些麻烦(注意使用 click.foo 而不是 click，因为 foo 是命名空间):
<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script>
$(document).ready(function(){
function turnOn() {
$("p").on("click.foo", function(){
$(this).css("background-color", "pink");
});
}
turnOn(); // initial setup
$("#turn-off").click(function(){
$("p").off("click.foo");
$('p').css("background-color", "white");
});
$("#reverse").click(turnOn);
});
</script>
</head>
<body>
<p>Click this paragraph to change its background color.</p>
<p>Click the button below and then click on this paragraph (the click event is removed).</p>
<button id='turn-off'>Remove the click event handler</button>
<button id='reverse'>Reverse the removal of the click event handler</button>
</body>
</html>